A buddy of mine uses this technique. Sometimes, he has trouble sleeping, and he read this somewhere. He says it works.
Lay down. Get comfortable. Regulate your breathing. Clear your mind, and then go through the process of visualizing and trying to feel each part of your body, starting from your toes, all the way up to your scalp, relaxing one after the other. Try to flex the muscles, wear out the tension and then let it relax.
Idealy, it should be like counting sheep. Like you'd fall asleep before you finished. Just try not to worry about an innability to sleep. Don't think about it. Just do it. If it doesn't work the first time, start at the top of your body and go through it again.